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Urospora penicilliformis

(Roth) J.E. Areschoug

Key Characteristics

  • Fine dark green slick "hair" (unbranched filaments) on upper intertidal rocks
  • Often dry

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Database links

UC specimens and range limits for Urospora penicilliformis

  • Blue markers: specimen records
  • Yellow marker: type locality, if present
  • Red markers: endpoints of range from literature

View map from the Consortium of Pacific Northwest Herbaria

Notes: On the Pacific coast, occurring at 40 of 41 sites from San Simeon, California, to Homer, Alaska (Hanic 2005). This species has been demonstrated to be conspecific with U. penicilliformis in the Atlantic Ocean.

Status: This species has been studied in culture (Hanic 2005) and with molecular analyses (Lindstrom & Hanic 2005). Hanic (2005) concluded that none of the Urospora specimens that he collected could be confidently identified using vegetative morphological characters (cell size and shape, chloroplast shape and colour, or rhizoid number). He also noted that Kornmann (1966b) reached the same conclusion. Features of the gametes can be diagnostic, as are crossing experiments. The habitats of the two species (U. penicilliformis and U. wormskoldii) on our coast are different, but often overlap. The presence of U. doliifera needs confirmation.

Habitat: On rocks, pebbles, boats, buoys, tires, logs and pilings, mostly in the upper littoral. Occasionally extending into the lower littoral (upper edge of the Laminaria zone) (Hanic 2005)

Life History: Urospora species reproduce asexually by four-flagellated quadrate acuminate zoospores and sexually by biflagellate gametes; the life cycle also includes a single-celled, uninucleate "Codiolum" phase of zygotic or parthenogenetic origin (Hanic 2005).

Associated Taxa: Pyropia, Bangia,

Search Sequences in GenBank

Urospora Areschoug 1866

Thalli with filaments unbranched, conspicuous for modified basal rhizoidal portion, unlike any other unbranched green algae. Rhizoids from several consecutive cells at base of filament, either emerging directly from a cell or growing downward for some distance between wall layers. Cell division intercalary and occurring in all but lowermost cells. Cells uninucleate or multinucleate. Chloroplast band-shaped or reticulate, with few to many pyrenoids. Vegetative reproduction by fragmentation. Quadriflagellate zoospores distinguished by long-attenuate posterior portion, or by akinetes. Sexual reproduction by biflagellate gametes; zygote developing into free-living "Codiolum" stage (see p. 95), producing quadriflagellate zoosporangia. Life stages heteromorphic.

Urospora penicilliformis (Roth) Aresch.

Conferva penicilliformis Roth 1806: 271. Urospora penicilliformis (Roth) Areschoug 1866: 16; Smith 1944: 64. Chaetomorpha catalinae Dawson 1949b: 2.

Filaments 3-4 cm tall, rather uniform in width; rhizoids at base of filament growing downward external to cell walls; cells 32-55(100) µm diam., 0.5-2 times longer, multinucleate; chloroplast reticulate, with many pyrenoids.

Abundant when found, but discontinuous in distribution, usually on rounded boulders making dark green, slippery, hairlike coating, high intertidal, Alaska to S. Calif. Type locality: Germany.

Excerpt from Abbott, I. A., & Hollenberg, G. J. (1976). Marine algae of California. Stanford University Press, Stanford, California. xii [xiii] + 827 pp., 701 figs.

Notes: Here follows an extract from the amended description, featuring vegetative features (Hanic 2005). See the paper for details of the reproductive cells.

Urospora penicilliformis (Roth) Areschoug (sensu Kornmann 1961b, 1966b)

Gametophytic thalli are uniseriate filaments, 4-50 mm long (up to 200 mm lower on the shore), composed of multinucleate cells ranging from squat or quadrate to barrel-shaped to elongate, (20-)50-80(-100) µm in diameter (average 57 µm, up to 192 µm lower on the shore), with a width:length ratio of 0.6-1.5 when mature. The holdfast is made of 1-12 (average 6) rhizoids in field material. Sexuality is most common in thalli from the upper littoral but rare in those from the lower littoral; gametangia have a maximum diameter of 250 µm. The plants are dioecious, rarely monoecious, and anisogamous. Zygotes reach 1-2 mm in length in nature.

Classification: Algaebase


Vertical Distribution: High intertidal

Frequency: Occasional

Substrate: Rocks, wood, floats, and other human-made substrates

Type locality: North Sea: near Eckwarden and Norderney I.

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Copyright © 2018 Regents of the University of California
Citation for this page: Urospora penicilliformis, in Kathy Ann Miller (ed.), 2018 California Seaweeds eFlora, [accessed on October 23, 2018]
Citation for the whole website: Kathy Ann Miller (ed.) 2018. California Seaweeds eFlora, [accessed on October 23, 2018].

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